Glossary

Question 0

Describe the method of limits to establish an absolute threshold

Answer 0

Gradually changing the properties of an imperceptible sound until it can be detected.
Set increments in stimuli can cause bias
The other method is called the method of constant stimuli…

Question 1

Define Absolute Threshold….

Answer 1

The smallest possible value of a stimulus that a participant can hear

Question 2

Describe the method of constant stimuli to establish an absolute threshold of sound….

Answer 2

Set of stimuli decided prior to test
Prevents bias
Stimuli are presented randomly to prevent bias

Question 3

Define difference threshold…

Answer 3

The smallest detectable difference between two stimuli - results in JND - just noticeable difference

Question 4

Webers law……

Answer 4

The bigger the stimulus, the bigger the bigger the increment of intensity needed for a change to be detectable
See page 224
K = webers constant
Stimulus intensity = I
Change in intensity which results in a JND =delta I

Delta I/standard stimulus = K

Question 5

What is a Phon?

Answer 5

The unit used to describe or measure the loudness of a signal
The loudness in phons is the level in dB SPL of an equally loud 1000 Hz tone.

Question 6

Describe auditory adaptation….

Answer 6

Auditory receptors reduce their response to a sustained stimulus so the energy used to respond matches the energy available to sustain it

Question 7

What is a harmonic?

Answer 7

Harmonics are frequencies which are multiples of the fundamental frequency
Therefore is the fundamental frequency is 100Hz the harmonics would be 200 Hz, 300Hz and 400hz
The higher the harmonic, the lower the amplitude of the wave

Question 8

What is sound intensity measured in?

Answer 8

Decibels dB

Question 9

What is absolute pitch?

Answer 9

A person has absolute pitch if they are able to identify the pitch of a tone in isolation with no external reference

Question 10

Define relative pitch?..

Answer 10

Ability to identify relations between pitches using an external reference

Question 11

Describe the features of pitch…

Answer 11

Pitch is subjective and closely related to the frequency of the sound….high frequency is perceived as high pitch and vice versa

Intensity has an impact on pitch perception
Tones below 2000Hz…pitch perception decreases as intensity increases
At frequencies above 4000Hz this is reversed

The JND is very small between pitches…easily distinguished during temporal code

Sounds that give a perception of pitch are periodic waves with fundamental frequencies and various harmonics
With complex waveforms the perceived. Pitch is close to that of the fundamental frequency

Question 12

Describe the perception of timbre..

Answer 12

Perception of timbre is complex as it is multidimensional

Timbre is partly determined by its relative amplitude of its various harmonics as well as temporal features

Question 13

List the three theories of speech perception…

Answer 13

The motor model

Invariant feature or cue based theories

The TRACE model

Question 14

Describe the motor model of speech perception

Answer 14

Speech is perceived using phonetic gestures performed by the speaker
Therefore speech perception is gestural not acoustic….movement not sound is therefore important
Studies have shown that while listening to sound, motor areas of the brain associated with speech production become active

Question 15

Describe the cue based/invariant feature theory of speech perception…

Answer 15

Studies phonetic gestures that do not change/vary
Speech is processed in a number of steps
1- detection of peaks and troughs etc in frequencies to provide landmarks
2 - extraction of cues from landmarks to determine action of lips and tongue (articulators)
3 - combination of landmark info and articulators to derive a specific segments
4 - segment info compared with banked sege,tn info to provide candidate words
5 - synthesis of sound patterns of candidate words to see which is a best fit to the auditory input

Question 16

Describe the TRACE model of sound perception…..

Answer 16

TRACE uses neural networks with interconnecting units (nodes) that classify incoming signals by comparing them with stored information
The nodes collect information and fire when their requirement have been met.
Need to look at these models more closely

Question 17

When speech is processed via the ventral stream the STS and STG are activated bilaterally. What does STS and STG stand for?

Answer 17

STS = superior temporal sulcus (phonological processing)
STG = superior temporal gyrus
Both activated in the ventral stream of auditory information from A1 (primary auditory cortex)

Question 18

Define conductive hearing loss….

Answer 18

Conductive hearing loss refers to a loss of hearing due to damage to the outer or middle ear
Auditory discrimination is usually unaffected and can be treated by hearing aids which simply amplify sound

Question 19

Define cochlear hearing loss….

Answer 19

Hearing loss caused by damage to the inner ear
Auditory discrimination is usually affected
Hearing aids do not help treat this condition

Question 20

Define retro cochlear hearing loss….

Answer 20

Hearing loss caused by damaged to the cochlear nerve between the cochlear and the brain stem
Irreversible condition
Results in loss if sound intensity and sound discrimination

Question 21

Define central hearing loss…

Answer 21

Hearing loss originating from the brain

Question 22

Define sensorineural hearing loss…

Answer 22

Caused by either cochlear, retro cochlear or central origins

Question 23

What is dB HL?

Answer 23

Decibels (hearing level) - recorded by an audiometer. Does not compare to standard reference pressures of 20 microPa therefore not dB SPL

Question 24

What is an audio gram?

Answer 24

When testing for auditory impairment an individual is provide with a number of frequencies of sound via headphones
The intensity of the frequencies are plotted on the y axis (in dB HL) of an audiograph while the frequency is plotted on the x axis (logarithmic scale) 0 dB HL would show unimpaired hearing

Question 25

Define auditory discrimination…

Answer 25

The ability to discriminate between sounds in a noisy environment

Question 26

Define typanosclerosis…

Answer 26

Scaring to the tympanic membrane which causes stiffness and reduces he ability to transmit sound waves

Question 27

What is otitis media with effusion?

Answer 27

This is the medical term for glue ear and is caused by a thick viscous fluid filling the middle ear when the Eustachian tubes are blocked by infection, swollen adenoids or immaturity of the tubes in young children
## most common cause of conductive hearing loss##

Question 28

What is a cholesteatoma?

Answer 28

Caused when negative pressure within the middle ear sucks part of the tympanic membrane in which then traps dead skin cells and forms a growth called a cholesteatoma which eats away at healthy tissue and oven damages the incus

Question 29

What is otosclerosis?

Answer 29

Caused when new bone forms around the ossicles in the ear preventing the transduction of sound waves

Question 30

Define prebycusis…….

Answer 30

A decrease in cochlear sensitivity with increasing age
Inner and outer hair cells are damaged by free radicals
Other contributing factors are DNA damage over time and a reduction in cellular protective mechanisms
Hearing loss is usually bilateral and greater at higher frequencies

Question 31

What is a cochlear implant?

Answer 31

A small electrical device containing electrodes which are placed on the cochlear, producing an electrical current and therefore stimulating the cochlear nerve

Question 32

What is a vestibular schwannoma or acoustic neuroma?

Answer 32

A benign tumour found in the inner auditory meatus, a bony canal which travels towards the brain stem
Caused by unstable Schwann cells
Results in unilateral hearing loss and tinnitus

Question 33

What is stereotactic radio surgery?

Answer 33

Machine aims radioactive cobalt 60 isotopes which emits high frequency gamma rays at the tumour
It can stop or reduce rumour growth